In order to compromise with the advancement in integrated printed circuit production, more and more electronic components are designed and constructed into microelectronic parts so as to enhance the efficiency of the integrated printed circuit. Under this condition, an electronic component, which is mounted on the integrated printed circuit by the conventional THT (through hole technology) assembly method, occupies a relatively large space on the printed circuit since the size of the electronic component cannot be minimized further. The THT assembly method includes a step of drilling a through hole in the printed circuit board in order to permit insertion of a mounting leg of the electronic component. The electronic components therefore occupy a large space on both sides of the printed circuit board. The soldering spot conducted at the respective hole in order to secure the leg of the electronic component relative to the integrated printed circuit is relatively large.
Presently, SMT (surface mounted technology) is used to mount the microelectronic parts on the integrated printed circuit. There is no need of drilling through holes in the printed circuit board and the microelectronic parts can be attached on the same side of the printed circuit board by soldering means. Alternatively, the microelectronic parts can be soldered on both sides of the integrated printed circuit in order to enhance maximum use of space and efficiency thereof. The mounting technology (SMT) costs lesser manufacture expense in comparison with the conventional mounting THT method. The trench to reduce the size of the microelectronic parts from 0603(1.6×0.8×0.45 mm) specification to 0402(1×0.5×0.35 mm) specification is inevitable, because the microelectronic part of 0402 specification occupies a space lesser than one half of the microelectronic part of 0603 specification. Thus, there arise several difficulties when mounting of the microelectronic parts onto the integrated printed circuit is conducted by means of SMT.
FIG. 1 is a fragmentary view of a specific delivery system 10 for delivering the microelectronic parts of 0603 or 0402 specifications to a predetermined position during assembly of electronic parts so as to form an electronic device, such a motherboard. As illustrated, the delivery system 10 includes a planar supply tray 12, a conveyer belt disposed at one side of the supply tray 12 for conveying a band carrier 14 to a predetermined position, and a peel-off device 16.
Referring to FIG. 2, a perspective view, illustrating interrelationship among the band carrier 14, a transparent tape 18 and the peel-off device 16. The band carrier 14 is formed with a row of uniformly spaced-apart retention recesses 141, within which pluralities of microelectronic parts 20 are disposed respectively. The band carrier 14 is further formed with a row of circular thorough holes 142 which are to be hooked by the conveyer belt so as to bring along the band carrier 14 together therewith when the conveyer belt moves toward the predetermined position. In order to prevent untimely removal of the microelectronic parts 20, the transparent tape 18 overlaps the band carrier 18 so as to cover and protect the microelectronic parts 20. Since the outer surface of each of the microelectronic parts 20 is coated with adhesive means, the transparent tape 18 is prevented from undesired removal from the band carrier 14. The peel-off device 16 is disposed 10 above the conveyer belt, and has a front end portion contacting forcibly and slidably the band carrier 14 so as to remove the transparent tape 18 from the band carrier 14 into a first direction when the band carrier 14 moves with respect to the peel-off device 16 in a second direction opposite to the first direction, thereby exposing the microelectronic parts 20. Upon reaching the predetermined position, the respective microelectronic part 20 is picked up by a suction device (not shown), and is then transferred by a machine arm (not shown) onto a respective integrated printed circuit for securing thereto.
Referring to FIG. 3, one drawback of the aforesaid delivery system 10 resides in that during the tape peeling operation, the microelectronic part 20 may turn upside down due to collision between the peel-off device 16 and a leading end of the respective microelectronic part 20. The swift running of the band carrier 14 results in a sudden upside down turning of the respective microelectronic part 20 upon collision against the front end of the peel-off device 16. When such things happen, the microelectronic part 20 is mounted incorrectly on the respective printed circuit. Since the top and bottom ends of each of the microelectronic parts 20 are marked with different colors (such as black and white), the incorrectness is visible vividly. The assembler on the assembly line must exert a concerted effort to remove and replace the wrong microelectronic part. It is time-consuming and laborious.